The prior zinc oxide varistors (Metal Oxide Varistors) has particular nonlinear current-voltage characteristics. In use, once abnormal condition occurs, such as struck by lightning, disturbed by electromagnetic field, frequent switching of power switch and failure of power system, making the voltage in the circuit sharply increases over the break-over voltage of the zinc oxide varistors, thereby entering the conducting area. At this moment, the relationship between current (I) and voltage (V) is nonlinear known as Nonlinearity Parameter which may reach a value of tens or hundreds. At this moment, impedance of zinc oxide varistor may be lower, may be only a few ohms, making the overvoltage to form surge current and flow out, thereby protecting the connected electronic products or expensive components. The zinc oxide varistor is one kind of electronic ceramic component.
The electrode of the prior electronic ceramic component is commonly made of silver electrode material or copper electrode material. As shown in FIG. 1, a traditional electronic ceramic component has a plane shape of round or rectangle, with a silver electrode layer or copper electrode layer 112 covering on the electronic ceramic chip 111. However, since the silver electrode material is very expensive and the cost of the copper electrode material is also high, the prior single-layer silver electrode and single-layer copper electrode do not meet the requirement of modern electronics technique with products having high cost performance.
Moreover, when manufacturing silver electrode or copper electrode of the electronic ceramic component, people commonly uses fabrography to apply silver paste electrode material or copper paste electrode material and fires after that, and especially takes a step of firing in reducing atmosphere when manufacturing copper paste electrode.
The manufacturing steps of silver electrode of the prior electronic ceramic component concretely include loading material (swash plate), silver paste wire mark, drying, turn-over and wire mark, drying, firing. The manufacturing steps of copper paste electrode of electronic ceramic component concretely include loading material (swash plate), copper paste wire mark, drying, turn-over and wire mark, drying, firing in reducing atmosphere. Since the silver paste contains about 80% of silver and the copper paste contains about 70-80% of copper, using silver or copper paste as electrode material will cost a little high. The drying step is performed at a temperature of about 250° C., the firing step is performed at a temperature of about 600° C., and the reducing atmosphere step using fabrography to apply copper electrode material need to be performed in millions worth of nitrogen-hydrogen atmosphere furnace, which will consume large amounts of nitrogen-hydrogen and more than an hour to fire in reducing atmosphere. Therefore, the disadvantages of the prior art that using fabrography to apply silver paste electrode material or copper paste electrode material are complicated technological process, time-consuming production process, high cost of electrode material and equipment, etc.